High-Resolution spectral models of TRAPPIST-1e seen as a Pale Blue Dot for ELT and JWST observations

TL;DR

This paper models high-resolution reflection and emission spectra of TRAPPIST-1e under various atmospheric and surface conditions to aid future ELT and JWST observations in detecting biosignatures and climate indicators.

Contribution

It provides a comprehensive high-resolution spectral database for TRAPPIST-1e with different atmospheric compositions and surface albedos, supporting observational planning and data analysis.

Findings

Biosignature pairs like O₂+CH₄ and O₃+CH₄ are detectable in spectra.

Climate indicators such as CO₂ and H₂O show identifiable features.

Spectral models help optimize future observation strategies.

Abstract

Rocky exoplanets orbiting in the habitable zone (HZ) of nearby M dwarfs provide unique opportunities for characterizing their atmospheres and searching for biosignature gases. TRAPPIST-1e, a temperate Earth-sized exoplanet in the HZ of a nearby M dwarf, is arguably the most favorable target for ground- and space-based atmospheric characterization by the extremely large telescopes (ELTs) and the James Webb Space Telescope (JWST). To inform future observations in reflected and emitted lights using these upcoming telescopes, we simulate the high-resolution reflection and emission spectra for TRAPPIST-1e for both modern and prebiotic Earth-like atmospheric compositions. To demonstrate the effects of wavelength-dependent albedo on climate and spectra, we further simulate five albedo scenarios for each atmospheric composition: cloudy modern Earth-like, cloud-free modern Earth-like, cloudy ocean planet, 100 per cent cloudy planet, and wavelength-independent albedo of 0.31. We use the recent Mega-MUSCLES spectral energy distribution (SED) of TRAPPIST-1 for our models. We show that the O$_2$ + CH$_4$ and O$_3$ + CH$_4$ biosignature pairs as well as climate indicators (CO$_2$ and H$_2$O) show features in both high-resolution reflection and emission spectra of TRAPPIST-1e that the ELTs can search for. Our high-resolution database for modern and prebiotic Earth TRAPPIST-1e models with various surface compositions and cloud distributions provides a tool for observers to train retrieval algorithms and plan observation strategies to characterize this potentially habitable world.